diff mbox series

[net-next,v11,10/21] net: add helpers for setting a memory provider on an rx queue

Message ID 20250116231704.2402455-11-dw@davidwei.uk (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series io_uring zero copy rx | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next, async
netdev/apply fail Patch does not apply to net-next-0

Commit Message

David Wei Jan. 16, 2025, 11:16 p.m. UTC 
Add helpers that properly prep or remove a memory provider for an rx
queue then restart the queue.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 include/net/page_pool/memory_provider.h |  5 ++
 net/core/netdev_rx_queue.c              | 66 +++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

Comments

Jakub Kicinski Jan. 17, 2025, 1:50 a.m. UTC | #1 
On Thu, 16 Jan 2025 15:16:52 -0800 David Wei wrote:
> Add helpers that properly prep or remove a memory provider for an rx
> queue then restart the queue.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> Signed-off-by: David Wei <dw@davidwei.uk>

Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Jakub Kicinski Jan. 17, 2025, 1:52 a.m. UTC | #2 
On Thu, 16 Jan 2025 15:16:52 -0800 David Wei wrote:
> +	ret = netdev_rx_queue_restart(dev, ifq_idx);
> +	if (ret)
> +		pr_devel("Could not restart queue %u after removing memory provider.\n",
> +			 ifq_idx);

devmem does a WARN_ON() in this case, probably better to keep it
consistent? In case you need to respin
David Wei Jan. 17, 2025, 2:17 a.m. UTC | #3 
On 2025-01-16 17:52, Jakub Kicinski wrote:
> On Thu, 16 Jan 2025 15:16:52 -0800 David Wei wrote:
>> +	ret = netdev_rx_queue_restart(dev, ifq_idx);
>> +	if (ret)
>> +		pr_devel("Could not restart queue %u after removing memory provider.\n",
>> +			 ifq_idx);
> 
> devmem does a WARN_ON() in this case, probably better to keep it
> consistent? In case you need to respin

Yeah I see it, thanks. It looks like I need to respin so I'll fix it up.
Jakub Kicinski Jan. 17, 2025, 2:25 a.m. UTC | #4 
On Thu, 16 Jan 2025 15:16:52 -0800 David Wei wrote:
> +static void __net_mp_close_rxq(struct net_device *dev, unsigned ifq_idx,
> +			      struct pp_memory_provider_params *old_p)
> +{
> +	struct netdev_rx_queue *rxq;
> +	int ret;
> +
> +	if (WARN_ON_ONCE(ifq_idx >= dev->real_num_rx_queues))
> +		return;
> + 
> +	rxq = __netif_get_rx_queue(dev, ifq_idx);

I think there's a small race between io_uring closing and the netdev
unregister. We can try to uninstall twice, let's put

	/* Callers holding a netdev ref may get here after we already
	 * went thru shutdown via dev_memory_provider_uninstall().
	 */
	if (dev->reg_state > NETREG_REGISTERED &&
	    !rxq->mp_params.mp_ops)
		return;

here, and in dev_memory_provider_uninstall() clear the pointers?

> +	if (WARN_ON_ONCE(rxq->mp_params.mp_ops != old_p->mp_ops ||
> +			 rxq->mp_params.mp_priv != old_p->mp_priv))
> +		return;
> +
> +	rxq->mp_params.mp_ops = NULL;
> +	rxq->mp_params.mp_priv = NULL;
> +	ret = netdev_rx_queue_restart(dev, ifq_idx);
> +	if (ret)
> +		pr_devel("Could not restart queue %u after removing memory provider.\n",
> +			 ifq_idx);
> +}
Pavel Begunkov Jan. 17, 2025, 2:47 a.m. UTC | #5 
On 1/17/25 02:25, Jakub Kicinski wrote:
> On Thu, 16 Jan 2025 15:16:52 -0800 David Wei wrote:
>> +static void __net_mp_close_rxq(struct net_device *dev, unsigned ifq_idx,
>> +			      struct pp_memory_provider_params *old_p)
>> +{
>> +	struct netdev_rx_queue *rxq;
>> +	int ret;
>> +
>> +	if (WARN_ON_ONCE(ifq_idx >= dev->real_num_rx_queues))
>> +		return;
>> +
>> +	rxq = __netif_get_rx_queue(dev, ifq_idx);
> 
> I think there's a small race between io_uring closing and the netdev
> unregister. We can try to uninstall twice, let's put

They're gated by checking ifq->netdev in io_uring code, which is
cleared by them under a spin. So either io_uring does
__net_mp_close_rxq() and ->uninstall does nothing, or vise versa.

> 	/* Callers holding a netdev ref may get here after we already
> 	 * went thru shutdown via dev_memory_provider_uninstall().
> 	 */
> 	if (dev->reg_state > NETREG_REGISTERED &&
> 	    !rxq->mp_params.mp_ops)
> 		return;
> 
> here, and in dev_memory_provider_uninstall() clear the pointers?
> 
>> +	if (WARN_ON_ONCE(rxq->mp_params.mp_ops != old_p->mp_ops ||
>> +			 rxq->mp_params.mp_priv != old_p->mp_priv))
>> +		return;
>> +
>> +	rxq->mp_params.mp_ops = NULL;
>> +	rxq->mp_params.mp_priv = NULL;
>> +	ret = netdev_rx_queue_restart(dev, ifq_idx);
>> +	if (ret)
>> +		pr_devel("Could not restart queue %u after removing memory provider.\n",
>> +			 ifq_idx);
>> +}
diff mbox series

Patch

diff --git a/include/net/page_pool/memory_provider.h b/include/net/page_pool/memory_provider.h
index 4f0ffb8f6a0a..b3e665897767 100644
--- a/include/net/page_pool/memory_provider.h
+++ b/include/net/page_pool/memory_provider.h
@@ -22,6 +22,11 @@  bool net_mp_niov_set_dma_addr(struct net_iov *niov, dma_addr_t addr);
 void net_mp_niov_set_page_pool(struct page_pool *pool, struct net_iov *niov);
 void net_mp_niov_clear_page_pool(struct net_iov *niov);
 
+int net_mp_open_rxq(struct net_device *dev, unsigned ifq_idx,
+		    struct pp_memory_provider_params *p);
+void net_mp_close_rxq(struct net_device *dev, unsigned ifq_idx,
+		      struct pp_memory_provider_params *old_p);
+
 /**
   * net_mp_netmem_place_in_cache() - give a netmem to a page pool
   * @pool:      the page pool to place the netmem into
diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index e217a5838c87..e934568d4cd9 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -3,6 +3,7 @@ 
 #include <linux/netdevice.h>
 #include <net/netdev_queues.h>
 #include <net/netdev_rx_queue.h>
+#include <net/page_pool/memory_provider.h>
 
 #include "page_pool_priv.h"
 
@@ -79,3 +80,68 @@  int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 
 	return err;
 }
+
+static int __net_mp_open_rxq(struct net_device *dev, unsigned ifq_idx,
+			     struct pp_memory_provider_params *p)
+{
+	struct netdev_rx_queue *rxq;
+	int ret;
+
+	if (ifq_idx >= dev->real_num_rx_queues)
+		return -EINVAL;
+	ifq_idx = array_index_nospec(ifq_idx, dev->real_num_rx_queues);
+
+	rxq = __netif_get_rx_queue(dev, ifq_idx);
+	if (rxq->mp_params.mp_ops)
+		return -EEXIST;
+
+	rxq->mp_params = *p;
+	ret = netdev_rx_queue_restart(dev, ifq_idx);
+	if (ret) {
+		rxq->mp_params.mp_ops = NULL;
+		rxq->mp_params.mp_priv = NULL;
+	}
+	return ret;
+}
+
+int net_mp_open_rxq(struct net_device *dev, unsigned ifq_idx,
+		    struct pp_memory_provider_params *p)
+{
+	int ret;
+
+	rtnl_lock();
+	ret = __net_mp_open_rxq(dev, ifq_idx, p);
+	rtnl_unlock();
+	return ret;
+}
+
+static void __net_mp_close_rxq(struct net_device *dev, unsigned ifq_idx,
+			      struct pp_memory_provider_params *old_p)
+{
+	struct netdev_rx_queue *rxq;
+	int ret;
+
+	if (WARN_ON_ONCE(ifq_idx >= dev->real_num_rx_queues))
+		return;
+
+	rxq = __netif_get_rx_queue(dev, ifq_idx);
+
+	if (WARN_ON_ONCE(rxq->mp_params.mp_ops != old_p->mp_ops ||
+			 rxq->mp_params.mp_priv != old_p->mp_priv))
+		return;
+
+	rxq->mp_params.mp_ops = NULL;
+	rxq->mp_params.mp_priv = NULL;
+	ret = netdev_rx_queue_restart(dev, ifq_idx);
+	if (ret)
+		pr_devel("Could not restart queue %u after removing memory provider.\n",
+			 ifq_idx);
+}
+
+void net_mp_close_rxq(struct net_device *dev, unsigned ifq_idx,
+		      struct pp_memory_provider_params *old_p)
+{
+	rtnl_lock();
+	__net_mp_close_rxq(dev, ifq_idx, old_p);
+	rtnl_unlock();
+}